Barosaurus ‭(‬heavy lizard‭)‬

Short Info

Barosaurus ‭(‬heavy lizard‭)‬

Phonetic : B‬ar-roe-sore-us.

Named By : Othniel Charles Marsh‭ ‬-‭ ‬1890

Diet : Herbivore

Size : Estimated 20-27 meters long

Type of Dinosaur : Sauropod

Type Species : B.‭ ‬lentus‭ (‬type‭)‬

Found in : Tanzania, USA,‭ ‬including the states of‭ ‬Colorado,‭ ‬Oklahoma,‭ ‬South Dakota,‭ ‬Utah and Wyoming‭ ‬-‭ ‬Morrison Formation

When it Lived : Late Jurassic, 155-145 million years ago

Barosaurus (/,baeroU’so:r@sBARR-o-SAWR@s) was a huge Long-tailed, long necked, plant-eating dinosaur that was closely similar to the much-loved Diplodocus. The remains have been discovered inside the Morrison Formation from the Upper Jurassic Period of Utah and South Dakota. It is located within the stratigraphic zone 2-5.


Barosaurus mount 1
Greg from New York, NY, America, CC BY 2.0, via Wikimedia Commons


The term “barosaurus” is a composite. Barosaurus originates in the Greek word barys (barus) meaning “heavy” and sauros (sauros) meaning “lizard”; thus “heavy lizard”.

Barosaurus was a huge animal and some adults measured between 25 and 27 metres (82-89 feet) in length and weighting around 12-20 metric tonnes (13-22 shorter tons). There are hints of larger animals like the massive vertebra found in the BYU 9024 specimen, which measures 1.37 meters (4.5 feet) long. If it’s believed to be a member of Barosaurus the animal that measured 48 meters (157 feet) in length and about the weight of 66 metric tons (73 short tons) in weight. This makes it the biggest known dinosaurs, having neck lengths of at minimum 15 meters (49 feet) as per Mike Taylor. In 2020 , Molina Perez and Larramendi have estimated that it was somewhat smaller, at 45 meters (148 feet) as well as 60 metric tonnes (66 short tons). However, the abstracts of SVP reveal that it was assigned BYU 9024 in the category of Supersaurus. Barosaurus had a different proportional distribution than its closest cousin Diplodocus and Diplodocus, having a larger neck and a shorter tail however, it was roughly the same size overall. It was larger than Apatosaurus however its skeleton had less strength.

Sauropod skulls aren’t usually preserved scientists are yet to find the Barosaurus skull. Diplodocids with similar characteristics to Apatosaurus and Diplodocus had large low skulls that had teeth that were peg-like and confined to face of their jaws.


Full Barosaurus, Royal Ontario Museum
KristyVan, CC BY-SA 3.0, via Wikimedia Commons


The majority of the distinctive characteristics of the skeletal structure of Barosaurus were found in the vertebrae. However, a complete vertebral column been discovered but has never been located. Diplodocus as well as Apatosaurus both were equipped with the same number of cervical (neck) and 10 dorsal (trunk) vertebrae, whereas Barosaurus only had nine dorsals. Dorsals could be converted to a cervical vertebra which would have resulted in sixteen vertebrae within the neck. The Barosaurus cervicals were comparable to the cervicals of Diplodocus however, they were also 50% bigger. The neural spines that protruded at the very tops of vertebrae weren’t as long or as intricate in Barosaurus like the ones in Diplodocus. Contrary to the neck vertebrae, Barosaurus had shorter caudal (tail) vertebrae than Diplodocus and this resulted in a tail that was shorter. The chevron bones that lined the tail’s underside were forked, and also had prominent forward spikes, similar to the closely related Diplodocus. The tail likely ended in a lengthy whiplash similar to Apatosaurus, Diplodocus and other diplodocids with some that were equipped with as many as 80 vertebrae in the tail.

The bones of the limbs of Barosaurus were almost identical to Diplodocus’s. Both were quadrupedal with columnar limbs that were adapted to accommodate the massive weight that the animal. Barosaurus had forelimbs that were proportionally longer as compared to other diplodocids. Nevertheless, they were smaller than the majority of other sauropods. There was only one carpal bone found in the wrist and the metacarpals were thinner than the metacarpals of Diplodocus. Barosaurus feet are not discovered, however, as with other sauropods it could be digitigrade, with each of the four feet carrying five tiny toes. A huge claw was adorning the inside of the digit on the manus (forefoot) while smaller claws pointed towards the outside three digits on the pes (hindfoot).

Initial Barosaurus remains were found within the Morrison Formation of South Dakota by Ms. E. R. Ellerman who was the postmistress of Pottsville and was the fossils were excavated in 1889 by Othniel Charles Marsh as well as John Bell Hatcher of Yale University in 1889. There were only six tail vertebrae found at the time, which formed the initial sample (YPM 429) of a brand new species that Marsh called Barosaurus lentus taken from the Classical Greek words barus (barys) (“heavy”) and sauros (sauros) (“lizard”) and the Latin word”lentus” (“slow”). The remainder of the specimen was buried in the soil in the care of landowner Ms Rachel Hatch, until it was retrieved nine years later in 1898 by Marsh’s assistant George Rieber Wieland. The new remains comprised of vertebrae, ribs, and limb bones. In 1896, Marsh had classified Barosaurus within the Atlantosauridae In 1898, it was classified by Marsh in the category of diplodocid in the very first instance. In his final article before passing away, Marsh named two smaller metatarsals identified at Wieland as a different species, called Barosaurus affinis but it has been considered to be a junior synonym of B. the lentus.

At the beginning of the 20th century the the Pittsburgh’s Carnegie Museum of Natural History sent fossil hunter Earl Douglass to Utah to dig the Carnegie Quarry in the area that is now called Dinosaur National Monument. Four neck vertebrae, each one meters (3 feet) long, were found in 1912 in the vicinity of an example of Diplodocus however, after a while, William Jacob Holland realized they belong to a different kind of. In the meantime, the most famous specimen of Barosaurus was finally prepared at Yale during January of 1917, and was thoroughly described in detail by Richard Swann Lull in 1919. According to Lull’s descriptions Holland made reference to his vertebrae (CM 1198) together with another partial skeleton discovered through Douglass at the time of his discovery in the year 1918 (CM 11984) which was later referred to as Barosaurus. The second Carnegie remains on the rocks wall of Dinosaur National Monument and was not completely prepared in the 80s.

One of the largest specimens from Barosaurus lentus was uncovered from the Carnegie Quarry in 1923 by Douglass who is now employed by the University of Utah after the death of U.S. Steel founder Andrew Carnegie who had been funding Douglass his earlier research in Pittsburgh. The material from this specimen was initially distributed over three institutions. The majority of the back vertebrae and ribs, pelvis, hindlimb and the majority of the tail went to the University of Utah, while the neck vertebrae and some back vertebrae and the forelimb and shoulder girdle were taken towards the National Museum of Natural History in Washington D.C., and the tail’s vertebrae was placed in the Carnegie Museum in Pittsburgh. In 1929, however, Barnum Brown arranged for all of the materials to be delivered towards the American Museum of Natural History in New York City, where it remains to this day. A cast of the piece (AMNH 341) was controversially exhibited inside the foyer of the American Museum, rearing up to protect it’s young (AMNH 7530, currently classified in the classification Kaatedocus siberi) from the attack of Allosaurus fragilis.

In the last few years, more vertebrae as well as a pelvis were discovered from South Dakota. The bone (SDSM 25210, 25331 and) is within the collections of the South Dakota School of Mines and Technology in Rapid City.

Darren Naish has noted a common mistake in books from the late 20th century , which show Barosaurus as a brachiosaur like short-tailed sauropod, with an ax on its body and neck, and frequently curving the upper part of the neck in an U-shape. He cites it as an illustration of an Palaeoart meme. This was first noticed in a drawing from Robert Bakker in a 1968 article in which two Barosaurus were shown to have short tails as a result of a mix of foreshortening and one that obscured the other.

In 2007 the Paleontologist David Evans was flying to the U.S. Badlands when he found a reference to the Barosaurus skull (ROM 3670) in the collection of the Royal Ontario Museum in Toronto which he was about to became a curator. Earl Douglass had excavated this specimen in the Carnegie Quarry in the beginning of the 20th century. the ROM was able to acquire it through an exchange in 1962 with Carnegie Museum. The specimen was not displayed and was kept in storage until it was discovered in the hands of David Evans 45 years later. David Evans went back to Toronto and scoured the storage facilities and discovered numerous fragments, both big and small, from the skull. It’s now the centerpiece in the museum’s dinosaur exhibition located within the James and Louise Temerty Galleries of the Age of Dinosaurs. At nearly 27.5 metres (90 feet) in length, the specimen is the longest known dinosaur to ever be displayed in Canada. The fossil is around 40 percent complete. Because the skull of Barosaurus has not been discovered in the past, the ROM specimen is adorned with the head of Diplodocus. Each bone is placed on a separate armature , so it is able to remove from the bone to examination and later removed without affecting the remaining skeleton. (See the video “Dino Workshop” at reference.) The rush was to place the dinosaur on display after a mere ten weeks from arrival at Research Casting International in 2500 pieces However, not all bone fragments were placed. Furthermore, additional bones marked ROM 3670 have been stored in the storage. In the near future, more bones may add to the collection and the specimen could turn out to be the completeest known.’ (See the video “Dino Assembly” at reference.) The ROM specimen has been dubbed “Gordo.” John McIntosh believes that the ROM’s skeleton is that of the person represented by the four neck vertebrae that are labelled “CM 1198” in the collection of the Carnegie Museum.

It was 1907 when German paleontologist Eberhard Fraas discovered the skeletons and bones of two sauropods while on a trip towards the Tendaguru Beds in German East Africa (now Tanzania). The two specimens were classified by the new Genus Gigantosaurus and each skeleton representing a different type (G. africanus and G. robustus). But, the name was already applied to the fragmentary remains of a sauropod found in England. Both species were transferred into a new genus called Tornieria, in the year 1911. After further research of these remains, as well as other sauropod fossils discovered in the highly prolific Tendaguru Beds Werner Janensch moved the species once more and this time to within the North American genus Barosaurus. The year 1991 was when “Gigantosaurus” robustus was classified as a titanosaur and was placed into a brand new species, Janenschia, as J. robusta. In the meantime, many paleontologists thought “Barosaurus” africanus was also distinct from the North American genus, which was confirmed when the specimen was re-described in the year 2006. This African species, while closely connected to Barosaurus Lentus and Diplodocus that are found in North America, is now recognized in the field of Tornieria africana. The species Barosaurus was also reported to have been discovered in the Kadsi Formation in Zimbabwe in 1987. The material, however, is not well preserved and fragmentary and wasn’t properly identified as such, so the connection to Barosaurus is a bit shaky. It could represent Tornieria.

Source: Wikipedia